Fluid blast circuit breaker



June 2, 1942. w. E. PAUL 2,284,840

FLUID BLAST CIRCUIT BREAKER William E. Pam,

x/ Mlm H His Bvtnizzor-rwey` June 2, 1942. w. E. PAUL 2,284,840

FLUID BLAST CIRCUIT BREAKER Filed Nov. s, 193e s sneetsF-sheet 2 y m E s I r'wertor:

William E-Faul,

His AttQr-rweg.

w, u u

June/2', 1942. w. E. PAUL FLUID BLAST CIRCUIT BREAKER Filed Nov. 3, 1958 3 Sheets-Sheet 3 Inventor: Wlam E paul,

b #Wa MM yHis Att omey.

Patented June 2, 1942 lUNITED STATE New York Application N/)vember 3, 1938, Serial No. 238,632

11 Claims.

My invention relates to fluid blast circuit breakers, and more particularly to gas blast circuit breakers wherein a source of pressure, independent of the magnitude of the current to be interrupted, is utilized to effect arc interruption.

The principal object of my invention is the DIO- vision of an improved fluid blast circuit breaker that has high interrupting capacity and that is efficient and positive in operation throughout the entire rating of the circuit breaker.

More particularly, a further object of my invention is the provision of means in a iiuid blast circuit breaker for segregating or isolating metallic vapor formed by the arc at the coacting contact surfaces so that the portion of the arc path subject to the fluid blast, is substantially free of said metallic vapor.

A further object of my invention is the provision in a fluid blast circuit breaker of improved blast producing meansl including a supplemental source of stored energy for supplementing and sustaining the fluid blast at the arc.

A further object of my invention is the provision of an improved operating means in a fluid blast circuit breaker of the character above defined for relating the contact structure'to pneumatic operating means.

2,284,840 Y FLUID BLAST CIRCUIT Bananas' -William E.Paul, Schenectady, N. Y., assigner .to

General Electric Company, a

s *Pll'rlazlsi'll OFFICE assura corporation of ses -11944'1 (Cl. 20o-148) is, as the arc current increases, the blast pressure 'must besufilcientto overcomethis arc resistance or back pressure so as to permit high velocity gas flow through the arc path, particularly when the alternating current passes through the zero value.

Heretofore the principal method of overcoming the arc resistance or back pressure consisted in utilizing comparatively high source pressures or in splitting the arc into a number of sections, all

of which are subjected to a uid blast.

I have found that this arc back pressure can bc reduced, and the gas blast made more effective by segregating or isolating the metallic vapor that is evolved from the coacting contact surfaces by the To this end the insulating casing 3, preferably" at both sides of the blast passage 4, is provided with recesses or pockets I and 8 within which both terminals or extremities of the arc path are located in the separatedv position of the breaker My invention will be more fully set forth in the following description referring to the accompanying drawings, and the features of novelty which contacts shown by Fig. l. Since the contact material vaporized by the arc at one terminal at least characterize my invention will be pointed out with particularity in-the claims annexed to and forming a part of this speciiication.v A

Referring to the drawings, Fig. 1 is an elevational'view, partly in section and partly diagrammatlcally shown, of a fluid blast circuit breaker in the open circuit position vthereof embodying the present invention, Fig. 2 is a similar view showing the lcircuit breaker in the closed circuit position, and Fig. 3 is a modiedform oi' my invention illustrating a double-break type gas blast breaker.

'I'he iluid blast circuit breaker specifically illustrated by Figs. l and 2 comprises a pair of relaf tively movable contacts I and 2 'operable within an insulating casing 3 which forms a blast passage 4 for directing flow of gas through and transversely of the arc path upon separation of the contacts. The insulating casing I also' includes an karc chute l having so-called insulating arc splitters 6 into which the arcl is blown by the diminish the effectiveness of the gas blast. That fpassage l to engage the fixed contact I.

contact 2 is normally biased by ay spring I0 towards open circuit position, and in the closed be apparent that the metallic vapor in the arc path can be limited to a Very small amount.

As specifically illustrated,the contact I is substantially fixed and has a limited movement or wipe at the resilient mounting 9. The movable rod contact 2 is guided for reciprocal movement in the casing 3 and is operable across the blast The circuit position, referring to Fig. 2, engages the contact I within thepocket 1. Accordingly, when the breaker is opened, the arc is initially formed in the'pocket 1 and is drawn entirely across the blast passage l to the opposite pocket 8.

In view of the fact that an arc, so far as isI known. does not actually transport matter such as with respect to the gas blast intermediate portion of the are. The metallic vapor is vented from thel l pocketsiin any suitable way, as through opposite ends of the arc chute 5.

It will be noted that the blast passage Jextending transversely of the intermediate portion of the arc path is of divergingshape so that the blast has high" velocity at the intermediate portion of the arc opposite the aro splitters. The effectiveness of the gas blast is further increased by designing the blastpassage so that the maximum gas velocity is at the entrance to the arc splitters, as contrasted rwith the usual method wherein the maximum velocity is at the point where the arc is formed. By restricting the blast passage at the approach to the arc and by locating the splitters in the diverging part immediately beyond the are, the blast is made most effective at that point.

The operating means for the switch contacts comprises inthe present instance an operating rod I I that is related through tripping means, generally indicated at I2, to a piston |3. When the disengageable tripping device I2 releases the rod II with respect to the piston I3, the contact biasing spring I moves the contact 2 toward the open circuit position indicated in Fig. l. The circuit closing operation can be effected when the tripping device I2 is reset, as illustrated, by admitting gas under pressure to the piston cylinder I4, as by means of a manually controlled valve I5. The piston I3 in moving toward the opposite end of the cylinder'also compresses a spring I6 in addition to the circuit closing operation on the contact 2. l

Referring more specifically to the tripping device I2 a crank I1 having a xed pivot at I8 is connected at I9 to the piston rod extension 20. The crank I1 also has connected thereto a tripping magnet 2| and a coacting armature 22. As best illustrated by Fig. 2, the magnet and its armature are copivotally mounted on the crank 'Ihe magnet 2| is also connected at 24 to the crank for limited'movement with respect thereto. The' magnet and crank are normally biased in opposite directions as shown.

A latch V25, copivotally mounted with respect to the armature 22 at 23, is provided with a roller 26 adapted to engage the end of the switch A operating rod II. The latch 25 is also mounted at 2 1 for limited movement with respect to the magnet 2| and is resiliently biased toward latching position. The armature 22 has a lost-motion connection, such as a pin and slot connection indicated at 28, with latch 25 so as to deliver a ha'- ner blow to the latch in response to a tripping impulse.

When the device is in the closed circuit position, shown by Fig. 2. suitable energization of the magnet coil 2|', in a manner-hereinafter described, causes counterclockwise movement of the` armature 22 so as`to strike and tripA the latch 25. When the roller 26 moves beneath the operlatch 25, after limited movement of the crank I1, must rotate with said crank by reason of the lostmotion connections at 2l and 21.

When the piston stroke is completed, the apparatus is in the position shown by Fig. 2 wherein it is held against the bias of springs I0 and IS'by the gas pressure from the line 29. Accordingly, in the closed position of the switch, the valve I5 remains open and is closed by any suitable means after a circuit interruption. Gas leakage from the cylinder Il is prevented by the piston seating as a valve at I3'. The cylinder I 4 therefore functions both as an expansible reservoir for storing gas under pressure and as contact operating means.

For opening the breaker, as in response to an overload or short circuit, the usual current transformer 3l! can be related to suitable tripping relays for initiating both the gas blast and the circuit opening 'operation As shown, the current transformer 30 can actuate both a valve operating relay 3| for initiating the gas blast and a time delay relay 32 for actuating the tripping device I 2. The purpose of relay 32 is to synchronize the contact opening with the gas blast.

The relay 3| is operated instantaneously `in response to a tripping impulse at 3D to open the exhaust valve 33 for releasing the pressure at the lower side of the blast valve V. Normally the pressure is equalized on both sides of the valve by reason'of a bleed vent 3l and the valve is seated at 35 under bias of the valve spring 3I. Therefore, when the pressure is unbalanced by opening of the exhaust valve 33, the pressure in the cylinder Il causes instant opening of the valve V and a high velocity gas blast through the switch passage I. The stored blast energy'in the cylinder or reservoir Il, therefore, insures an imating rod II, the contact spring I0 operates the "through the iat-chas, It `will be noted'l that the mediate supply of a large volume of gas for blast purposes so that the supply line 29 need not be of large size. This is important where the gas supply must be conserved.

For the purpose of insuring a gas blast at the instant of contact separation, there is introduced a slight delay by means of relay 32 in actuating the tripping device I2. The relay 32 closes the` energizing circuit of the coil 2|' at 32 after a predetermined delay to trip the breaker in the manner above described.

Coincident with or slightly before the tripping operation, the piston spring I6 starts to deliver its stored energy to supplement and sustain the main arc interrupting blast. As the valve V opens, the pressure within the cylinder Il immediately drops so that the high initial' blast velocity would not be maintained except for the sustaining blast by the piston as. In view of the fact that the arc is generally interrupted within a very few cycles, it will be apparent that the piston I3 is effective to maintain the blast at high velocity for a suillcient interruption period.

It will be noted that the contact opening movement is independent of the speed of the return stroke of the piston. With this arrangement the stored energy imparted to the piston serves to maintain a high velocity blast across the arc path an appreciable time after full contact separation. 'Ihe arrangement also permits high speed opening of the switch since the opening spring III need accelerate only the movable contact and its operating rod.

The mechanism is reset when the piston I3 reaches the end of its stroke, as shown in Fig. l.

The tripping device I2 is rotated clockwise during the return stroke of the piston and the resilient connection'at 21 serves to bias the latch roller 26 behind the contact operating rod li at the end of the stroke. It will be noted that the mechanism is "trip-free near -the end of the closing ystroke since the latch can be actuated by the magnet 2l to release the contact 2 at .this part of the stroke.

The control means for the valve l5 can be of any suitable type and is shown as manually operated for purposes of clearness. It will be ,obvious, however. that a remote control system can be employed for opening the valve to initiate the closing operation and for automatically closing i the valve when the circuit is interrupted.

' Referring to the double-break modication illustrated by Fig. 3,.the gas blast circuit breaker comprises essentially a pair of xed terminal contacts 40 and 4l arranged to be engaged and bridged by a movable contact 42 having rod contact portions 43 and 44. The rod contacts 43 and 44 make butt contact engagement with the iixed contacts and are resiliently mounted at 43' and 44', respectively, on the bridging member for limited overtravel or Wipef The bridging member is operated by a pair of insulating rods 45that are operatively connected to a piston 4i through a resilient connection 4l. The piston 46 in turn is connected to an operating rod 4l guided with -respect to the piston cylinder 49. The

operating rod can be connected to suitable actuating mechanism (not shown). It will, therefore, be noted that the arrangement is such that opening movement of the contacts through the operating rod 48 also is accompanied by move ment of the piston 46' in a direction to direct a gas blast in thedirection of the contacts.

For/the purpose of directing the gas blast effectively into the arc paths formed between the separating contacts, the piston cylinder 49 is adapted to communicate with an arcing chamber and chute structure generally indicated at 50. I'he arc chute includes a pair of insulating arc chambers 5I and 52 separated in the present instance by an insulating partition 53. Each chamber is arranged to be in communication with the cylinder 49 through passages 5I' and 52 respectively. The contacts 43 and 44 in opening pass through the chambers 5I and 52, respectively, and a plurality of arc splitters 54 are disposed in the chute transversely of the arc path atthe opposite open sides of the arc chambers. I'hc arc gases are therefore directed in opposite directions from the two breaks so that the danger of flash-over, where high voltages are in volved, is minimized.

For the purpose of segregating the metallic vapor formed by the arc, the arcing chambers 5I arc at high voltages. Another important advantage is that' the loop inthe circuit at the arc chambers causes the magnetic forces to be utilized so as to assist the gas blast in driving the arcs into the arc splitters. That is, the magnetic forces set up by the current to be interrupted tend to drive the arcs into the arc splitters independently of the gas blast so that the latter thereby can be even more effective.

In operation it will be noted that the lost motion resilient connections at"41 between the piston 46 and the bridging contact 42 permits an initially high acceleration independently of the bridging contact so that there is present an effective gas blast at the instant of contact separation. After predetermined travel of the piston 48, the contact rods 45 are directly engaged to insurefpositive separation oi the contacts. This contact opening speed is very high since the movable contact structure is automatically picked up and accelerated by the` inertia of the piston and operating mechanism which are at this point moving at high speed.

It should be understood thatmy invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric air circuit breaker of the cross .blast type comprising relatively movable contacts, independent pressure means for directing and 52 are arranged so that both terminals of the arc can be exteriorly lof the arc chambers, and vhence removed from the main gas blast, when the contacts are in the separated position shown. vertical spaced relation. the ilxed contacts so as to form pockets 55 and 56 for segregating the metallic vapor at the points of initial arc formation. As illustrated, the metallic vapor is vented at opposite sides of the arc chute and does not enter the arc path. In the same manner the metallic vapor at the contacts 43 and 44 can be vented through the upper open end'of the chute.

An advantage of the present arrangement is arc splitters. provides a comparatively long 'creepage path for preventing restriking of the To this end the chambers overhang, in

a fluid blast transversely through the arc path formed upon separation of said contacts, and means for segregating and dissipating metallic vapor formed by the arc at each contact surface at the opposite extremities of the arc path, said metallic vapor being dissipated in directions away from said are path so that the intermediate part of the arc path subject to said iiuid blast is substantially free of said vapor.

2. An electric air circuit breaker of the cross blast type comprising a pair of relatively movable contacts, an independent source of fluid pressure, insulating means forming a iluid passage from -said source. extending transversely of the arc path formed upon separation of said contacts, said insulating means forming pockets at opposite sides of said fluid passage and separate therefrom, and means for eiecting separation oi said contacts so that the extremities of the arc path are located substantially within said pockets, said pockets being vented independently of said iluid passages.

3. An electric air circuit breaker of the cross blast type comprisinga pair of relatively movable contacts', means forming a uid passage for directing under pressure a uid blast substantially transversely of and through an intermediate section of the arc path formed upon separation of said contacts, and insulting barrier means disposed adjacent each side of the said passage and oiiset with respect to said iluid blast beyond which each end of the arc is drawn for segregating metallic vapor formed at the corresponding contact surfaces, said insulating barrier means defining es for venting said metallic vapor to atmosphere independently of the arc path.

4. An electric circuit breaker of the gas blast type comprising relatively movable contacts, means for separating said contacts. passage means for directing a gas blast through the arc path ,formed upon contact separation, a main source of pressure for said gas blast, and a second supplementary source of blast energy including a spring arranged normally to be held under tension by the pressure from said first source, said main and supplementary sources both communicating with said passage means for interrupting the arc.

5. An electric circuit breaker of the gas blast type comprising relatively movable contacts, means for separating said contacts, means for directing a gas blast through the arc path formed upon contact separation, a source of pressure for said gas blast, a blast valve for controlling admission of gas from said source directly to said contacts, and a second supple' mentary source of blast energy including an expansibie reservoir arranged normally to be un- -der pressure from said rst source, said valve also controlling admission of gas from said reservoir to said contacts so that opening of said valve releases said reservoir energy for sustaining the blast from said first source.

6. An electric circuit breaker of the gas blas type comprising relatively movable contacts, a iluid passage for directing a gas blastpthrough the arc path formed by contact separation, a source of pressure for said gas blast, a blast controlling 'valve directly interposed with respect' to said source and passage, a cylinder having a spring biased piston arranged .to be in communication with said source in the closed position of said contacts independently of said blast valve whereby said piston is biased to a spring charging position, said valve also interposed with respect\to said piston and passage, and means for opening said blast valve whereby the gas blast from said source isV supplemented by said spring charged piston and directed through said passage for interrupting the arc upon separation of said contacts.

'1. An electric circuit breaker of the gas blast valve and tripping device.

type `comprising relatively movable contacts,

means for directing a gas blast through the arc path formed upon contact separation, a source of blast energy comprising a spring charged piston. and tripping means for relating vsaid piston to saidA contacts fwhereby circuit closing movement thereof is etl'ected coincident with the 9. A gas blast circuit breaker comprising separable contacts arranged form'v two breaks in series, insulating arc chamber Vmeans within which said breaks are formed, said chamber means having apertures through whichthe arcs at said breaks ,are drawn so that the extremities of said arcs are exteriorly of said chamber, said chamber also opening to' exhaust the arc gases at each break in opposite directions, the aforesaid exterior extremities of said yarc being vented directly to atmosphere independently of said chamber exhaust opening, arc splitters at said exhaust openings, means for directing gas under pressure into said chamber means upon separation of said contacts to interrupt arcing at said splitters, and means for operating said contacts.

10. A gas blast circuit breaker comprising a pairof iixed contacts, a coacting bridging contact arranged to form two breaks in thecircuit, insulating means including barriers extending transversely of the arcs at said'breaks for partially confining the arcs formed at said breaks, said barriers having apertures through which said arcs are drawn so that but theintermediate portions of each arc are coniined by said insulating means, said coniining means opening in opposite `directionscorresponding to the directions in which said arcs are biased by the magnetic forces thereof, the extremities of said arcs being vented directly to atmosphere independently of theopposite openings in said conning means, a plurality of arc splitters at said exhaust openings, and means for directing gas under pressure into said confining means to drive said arcs into said arc splitters in accordance with the contact opening operation. l

1l. A gas blastcircuit breaker comprising an insulating arc chute having a comparatively narrow entrance portion and a liiared exhaust portion, relatively movable contacts separable at said entrance portion, means deilning a uid passage for directing a-gas blast into said chute at said entrance portion and transversely of the arc path formed upon separation of said con.

v tacts, and a plurality of insulating are splitters contacts, and electroresponsive control means disposed in `said' chute and" extending edgewise in spaced flaring relation from points adjacent to said arc path toward the 'chute exhaust so as to define a plurality of blast 'passages through said chute, one oi' Asaid arc splitters forming with lsaid chute a passage off-set with respect .to said blast passages so'that'it is not traversed by the main gas blast, saidoflset passage being in rcornmunication with one of said contacts for'venting arcgases and vapors at said" contact independently4 of the main arc interrupting blast.

E.A PAUL. 

